and president obama and mitt romney, one day away from that first and crucial debate. both candidates cramming in private. the stakes could not be higher for romney behind now in the battleground states. abc's jake tapper is in las vegas where the president has set up his debate camp. good morning, jake. >> reporter: good morning, george. that's right, both campaigns have been intensity participating in mock debates. president obama working on keeping his answers concise. mitt romney, his aides say, is getting used to the one-on-one format, with the race so tight, anything could happen and so much could ride on tomorrow night. mitt romney held a rally in denver overnight, where he previewed tomorrow night's fireworks. >> these debates are an opportunity for each of us to describe the pathway forward for america that we would choose. and the american people have to make their choice as to what kind of america they want. >> reporter: he will likely start the day tomorrow with a workout. he's an elliptical machine kind of guy. meanwhile, the president is at this posh reso